Science - NCAR Climate Model Correctly Reruns Warming Period Of 130,000 BC

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A new examination of the period of global warming that planet Earth underwent 130,000 years ago is helping scientists to confirm the accuracy of projections for the next century - particularly over Canada's North. A team that includes University of Calgary glaciologist Dr. Shawn Marshall - the lone Canadian - will publish results of its research in the forthcoming issue of the journal Science. The paper shows that a sophisticated climate model, which is one of several global models used in projections of future climate change, is successful in recreating the last period of significant global warming.

"If the climate model is capable of reproducing a climate scenario that is consistent with the palaeological record, that gives us more confidence that it's also giving us reliable projections for the future," says Marshall, an associate professor in the U of C's Department of Geography and second author on the paper. Marshall, together with researchers from the U.S. National Centre for Atmospheric Research (NCAR), the University of Arizona and the University of Colorado, created a snapshot of climatic conditions 130,000 years ago using existing academic research.

The synthesis draws from ice core evidence, stranded coral reefs, fossilized pollen, and the chemical makeup of ancient shells in northern lakes and ocean sediments. The investigators then tested whether the NCAR climate model was able to simulate the extreme conditions of the time, which included loss of summertime sea ice in the Arctic and global sea levels about five metres higher than present.

"The difference 130,000 years ago is that there was an increase in solar radiation over the Arctic, caused by slight changes in the Earth-Sun orbit, which is a normal cycle that occur over tens of thousands of years," Marshall says. "This time around the warming is man-made, caused by carbon dioxide emissions, but the effects on Arctic sea ice, permafrost, and icefields are forecast to be similar."

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http://www.terradaily.com/reports/Glimpse_To_Past_Adds_Weight_To_Global_Warming_Forecasts.html